Disulfonate anti-caking agents for straight-chain sulfonate detergents



United States Patent Ofiice 3,356,709 Patented Dec. 5, 1967 DISULFONATE ANTI-CAKING AGENTS FOR STRAIGHT-CHAIN SULFONATE DETER- GENTS David M. Marquis, Orinda, Calitl, assignor to Chevron Research Company, a corporation of Delaware N Drawing. Filed June 17, 1964, Ser. No. 375,937

14 Claims. (Cl. 260-468) ABSTRACT OF THE DISCLOSURE The present invention is directed to a process for suppressing the caking tendencies of straight-chain alkyl benzene sulfonate non-soap detergents containing 9 to 18 carbon atoms in the alkyl portion and to built solid detergent compositions thereof. The caking tendencies are suppressed by the incorporation of from 2 to 25% and preferably 8 to 25% by weight based on the non-soap detergents of a particular class of anticaking inhibitors; namely, disodium benzene disulfonate, dipotassium benzene disulfonate, disodium toluene disulfonate, and dipotassium toluene disulfonate.

The present invention relates to a process for suppressing the caking tendencies of alkyl aryl sulfonate detergents, and to the resulting detergent compositions having improved noncaking properties. More particularly it relates to the preparation of a particulate solid detergent composition containing alkyl-substituted aryl sulfonate organic detergent, the a kyl group substituted on the nucleus being of straight-chain structure, said detergent composition having uniformly dispersed therethrough a minor proportion of an anticaking agent to suppress the caking tendencies of said organic detergent.

For a great number of years the bulk of detergent alkylate used to make the finished detergent composition by conversion to the sulfonic acid, followed by neutralization, has been the monophenyl substituted polypropylene polymers, as described in US. Patents Nos. 2,477,382 and 2,477,383 to Lewis. While these detergent compositions have superior detcrsive powers, it was recognized early in their development that in the particulate solid form they where hygroscopic and possessed undesirable caking tendencies. These defects were particularly noticeable in built alkyl benzene sulfonate detergent formulations or compositions useful as household washing powders. To inhibit or prevent the undesirable caking phenomenon use was made of a number of anticaking agents, particularly satisfactory being sodium benzene sulfonate or sodium toluene sulfonate, as shown in US. Patent No. 2,773,833.

Because of the branched-chain nature of the alkyl polypropylene precursor used in making detergent alkylate, the subsequently sulfonated and neutralized detergent does not meet the recently specified requirements of biodegradability. Therefore, in order to produce a more biodegrad able detergent, there is being promoted a so-called linear alkyl benzene sulfonate (LAS), i.e., one derived from the sulfonation and neutralization of detergent alkylate in which the hydrocarbyl or alkyl radical is derived from straight-chain or normal hydrocarbons instead of polypropylene. To make the biodegradable detergent, conventional reactions involve catalytic alkylation of benzene or some other aryl compound, such as toluene or Xylene, with either an n-alkene or an n-alkyl halide alkylating agent of the desired molecular weight range, i.e., corresponding to a carbon content of 9 to 18 carbon atoms. The alkylating agent can be derived from petroleum distillate cracking or petroleum wax cracking, catalytic dehydrogenation of nparafi'lns, chlorination-dehydrochlorination of n-paraffins, ethylene polymerization, and chlorination of n-parafiins.

In addition, the raw materials from which the straightchain stock is to be derived may be, and often is, subjected to iso-normal separation processes, such as those involving molecular sieves and urea clathration to produce a more linear product than could otherwise be obtained.

Like the branched-chain polypropylene-based detergents, the linear alkyl benzene sulfonates possess undesirable caking tendencies. Indeed, the caking problem eems to be aggravated with the linear alkyl benzene sulfonates to the extent that known anticaking additives, although regarded as being satisfactorily effective in branched-chain alkyl benzene sulfonates, are often, on the other hand, not quite so effective with currently produced linear alkyl benzene sulfonates. Conversely, the presently contemplated anticaking inhibitors, although eminently effective in linear alkyl benzene sulfonate detergent compositions, are unexpectedly not so effective, when incorporated in the branched-chain alkyl benzene sulfonates, as the known inhibitors.

It has now been found that the caking tendencies of particulate solid linear alkyl benzene sulfonate detergent can be suppressed by intimately admixing therewith a small but effective proportion of an anticaking agent selected from the group consisting of disodium benzene disulfonate, dipotassium benzene disulfonate, disodium toluene disulfonate, and dipotassium toluene disulfonate. In general, a satisfactory amount of anticaking inhibitor can range from about 2 to 25%, preferably 8 to 20%, by weight, based on alkyl benzene sulfonate detergent.

The invention is applicable to built detergent compositions, i.e., compositions containing nonsoap linear alkyl benzene sulfonate synthetic detergent, and an inorganic .salt detergent builder, such as a sulfate, carbonate, silicate,

borate, or condensed phosphate sodium salt.

Therefore, a more specific embodiment of the invention is the preparation of a particulate solid detergent composition consisting essentially of nonsoap linear alkyl benzene sodium sulfonate detergent having caking tendencies, an inorganic sodium salt detergent builder, and a small but effective amount to suppress said caking tendencies of an anticaking inhibitor selected from the group consisting of disodium benzene disulfonate, dipotassium benzene disulfonate, disodium toluene disulfonate, and dipotassiuzn toluene disulfonate. The proportions of nonsoap synthetic detergent can range from about 5 to 95%, preferably 10 to 40%, by weight, based on it and detergent builder; inorganic detergent salt builder, from 5 to 95%, preferably 60 to by weight, based on it and nonsoap detergent; and anticaking agent from about 2 to 25%, preferably 8 to 20%, by weight, based on nonsoap synthetic detergent.

nonsoap synthetic detergent and a condensed phosphate such as tetra-sodium pyrophosphate and/or sodium tripolyphosphate, usually in a weight ratio of phosphate to synthetic detergent ranging from less than 1:1 to more than 3:1. Other inorganic salt detergent builders as well can be present to the extent that the total inorganic salt builder, including the phosphate, to synthetic detergent weight ratio can be as high as 10:1. Further as is known in the art, special purpose additives, such as a bleach, perfume, foam booster, etc., may be present in the finished composition in a combined amount up to 30 percent by Weight of the finished composition.

Accordingly, a particularly useful embodiment of the invention is the preparation of a heavy-duty particulate solid detergent composition, at least 70% by weight thereof consisting essentially of linear C C alkyl benzene sulfonate organic detergent, an inorganic salt detergent builder in a weight ratio to organic detergent ranging from 1:1 to 1, said inorganic salt detergent builders including a condensed sodium phosphate, such as tetra-sodium pyrophosphate and/ or sodium tripolyphosphate, present in a weight ratio to the organic detergent ranging from about 1:1 to 3:1; and the specified anticaking inhibitor in an amount of 2 to 25%, preferably 8 to by weight, of the organic detergent.

The anticaking preventive is incorporated in the detergent composition in such fashion as to effect intimate and thorough admixture with, or uniform dispersion throughout, the other components of the detergent composition. This can be accomplished by wet-mixing, such as. by forming an aqueous dispersion or slurry comprising the anticaking additive and other components of the composition, and then drying the dispersion.

A convenient way of effecting uniform dispersions of the anticaking inhibitor throughout the composition is to integrate its incorporation with the process of making the linear alkyl benzenes sulfonate detergent by adding the inhibitor at the neutralization step, as follows.

Appropriate aryl compound such as benzene or toluene, benzene hereinafter being taken as representative, is alkylated with an alkylating agent in the presence of an alkylating catalyst. Thus, benzene can be alkylated with a straight-chain olefin mixture, for example, a C C uolefin mixture, or any desired olefin fraction, such as C C or a C -C a-olefin fraction, in the presence of HF catalyst; or with a chloroparafiin of similarly varying carbon range in the presence of a Friedel-Crafts catalyst, such as Alcl The resulting mixture of C C monoalkyl benzenes is then sulfonated by means of a suitable sulfonating agent, such as sulfuric acid, oleum, or S0 to produce the alkyl benzene. sulfonic acids.

Following the sulfonation step, excess sulfonating agent can be removed from the sulfonation mixture by adjusting the water content of the mixture, settling to obtain a top sulfonic acid phase and a lower spent acid phase, which is discarded. The sulfonic acid phase is then neutralized with a suitable base, such as caustic or sodium carbonate to give the alkyl benzene sodium sulfonate.

It is often the practice to leave all or a part of the unreacted. sulfuric acid used in the sulfonation step admixed with the alkyl benzene sulfonic acids and to neutralize them together to form an aqueous dispersion or slurry of organic sodium alkyl benzene sulfonate and in- .organic sodium sulfate salt, the inorganic sulfate later serving as a builder in the finished detergent composition. The slurry is then dried as by spray-drying or drum-drying and reduced to the desired particle shape and size.

The anticaking inhibitor of the present invent-ion can be incorporated into the detergent composition by adding .benzene or toluene disulfonic acid, in amounts calculated to give the desired content of disalt in the finished product, to the sulfonation mixture to be neutralized or to the caustic solution used in the neutralization step, thereby converting the disulfonic acid, along with the alkyl benzene sulfonic acids, to the salt form. Or, if desired, pre formed disodium or dipotassium salts of the disulfonic acids of benzene or toluene can be added either to the neutralizing caustic solution or to the sulfonation mixture prior to or during the neutralization step.

As hereinabove indicated, in addition to inorganic sodium sulfate detergent builder, other inorganic salt deter-.

gent builders, such as the condensed phosphates, carbonates, silicates, and borates, can be incorporated in the detergent composition. These may be added to the neutralized slurry prior to drying in accordance with the specifications desired in the ultimate or finished composition. The slurry thus built is then converted to the pars ticulate solid form and size by a suitable drying operation such as spray-drying or drum-drying.

As stated, a particularly useful composition is one based on linear alkyl benzene sodium sulfonate detergent,

condensed phosphate ordinarily used in conjunction with a synthetic surfactant to produce a heavy-duty detergent composition. The polyphosphates can be used in their commercially available anhydrous form, obtained by the high-temperature dehydration of the orthophosphates tripolyphosphates, from a mixture of disodium orthophosphate and mono-orthophosphate; tetrasodium pyrophosphate, from disodium orthophosphate; and sodium polymeta-phosphates, from orthophosphate. The various condensed phosphates can be used singly or in admixture. As is known in the detergent art, the Proportions of the various phosphates are frequently altered in practice to meet the desired specification. Generally good results are obtained when sodium tripolyphosphate is essentially the sole condensed phosphate, or is admixed with the other condensed phosphate, for example, tripolyphosphate and 20% pyrophosphate.

In addition to the detergent builders, other ingredients or fillers, in combined amounts up to about 30 weight percent of the final composition, can be incorporated. Examples of optional ingredients are those customarily present in heavy-duty detergent formulations. These include in weight amounts based on final composition, an anticorrosion and stabilizing agent, such as, sodium silicate, wherein the SiO to Na O ratio can range from 1/ 2 to 2/1 in proportion of, for example, 5 percent; an anti-redeposition agent, such as carboxyrnethyl cellulose, as described for example in US. Patent No. 2,568,334, proportions of about 1 to 3 percent being cited as illustrative; a foam modifier, such as a monoor di-ethanolamide of a fatty acid, such as lauric isopropanolamide, in proportions, for example, of 5 percent; a chemical bleaching agent such as sodium perborate or sodium percarbonate, for example, in an amount of 2 to 5 percent, optical whiteners, in amounts of the order 0.1 to 0.2 percent, such as the triazinyl and aroylstilbenzene, such as benzidinesulphones, bisbenzimidazoles, triazoles, and amino coumarins; sequestering agents, in amounts, for example, of the order of less than one percent, such as tetrasodium ethylene diamine tetraacetic acid.

The following examples are given to *illustrate the invention, parts being by weight:

Example 1 (a) A mixture of linear alkyl benzene sodium sulfonates having 11-14 carbon atoms in the alkyl groups, and obtained by the AlCl alkylation of benzene with chlorinated C C normal paraffins, was dried to a constant weight on a hot plate at C. to produce a free-flowing powder.

The dried powder was placed in an uncovered jar and exposed to room conditions of temperature and humidity, that is, 21 C. and 55% relative humidity.

After 15 minutes the jar was sealed. The material was observed to be stuck to the bottom of the jar and could not be made to flow freely.

(b) Water solutions of the same detergent material as used in (a) and of sodium sulfate were mixed and dried to constant weight. The dried free-flowing mixture contained 50 parts linear alkyl benzene sodium sulfonates and 8 parts of sodium sulfate.

Under the same conditions as in (a), the free-flowing mixture was exposed in a jar for 15 minutes after which the jar was sealed. The mixture was found to be partly caked to the bottom of the jar, and could not be made to flow freely.

(c) Under-the same conditions as in (b), except that the sodium sulfate was replaced by an equal weight of disodium benzene disulfonate, after exposure for 15 minutes and sealing in the jar, no caking was observed, and the contents of the jar flowed freely.

Example 2 (a) Detergent like that of Example 1 containing 13.7 percent of sodium sulfate produced in the process of making the detergent was dried to constant weight as in Example 1 to produce a free-flowing granular composition. This composition was placed in a jar and exposed to the same atmospheric conditions as in Example 1 for 15 minutes, and then sealed. The detergent composition formed a cake which could be dislodged from the bottom of the jar only by severe shaking.

(b) 57 parts of the detergent-sulfate mixture of (a) was dissolved in water. To this solution was added 8 parts of disodium benzene disulfonate dissolved in water.

The resulting solution was dried to constant weight as in (a) to produce a free-flowing powder. This powder was placed in a jar, and exposed to the same conditions of temperature and humidity. After 15 minutes the jar was sealed. No caking was observed, and the material in the jar was free flowing.

A suitable method for determining the extent of caking in a built detergent composition, and the one utilized in the examples below, is the lift-tackiness test.

According to this test, the ingredients of the composi tion to be tested are formed into a water slurry of approximately 50% solids content. This slurry is mixed with a mechanical stirrer for 15 minutes and then dried on a glass plate. The glass plate is kept on a steam plate or hot plate which is kept at constant temperature in the range of 135150 C. The slurry is spread on with a large 3l-mil doctor blade and allowed to dry until the dried product is readily scraped off (2 to 4 minutes). The composition then contains l-2% moisture.

The powder is then screened and that passing through a 20 mesh screen and retained on a 48 mesh screen is used for testing.

The apparatus used in the test comprises a stationary aluminum cylinder having a diameter of 1%.", mounted above a spring pan balance supported on a screw-type jack. The bottom of the aluminum cylinder is covered with double-sided adhesive tape, which is changed with each test. The underside of the adhesive tape is coated with a thin layer of the test sample.

30 ml. of screened sample prepared as above is weighed, and is poured in the form of a conical pile on a piece of filter paper in a Petri dish having a diameter of 9 cm., supported on the pan of the balance. The top of the sample pile is spread level to the top of the Petri dish.

The jack is slowly raised and the test sample is made to impinge upon the treated bottom of the aluminum cylinder to a pressure of 100 g.

This pressure is maintained for 30 seconds, and then slowly released by lowering the jack. As soon as the Petri dish clears the sample adhering to the cylinder, a piece of stiff weighing paper is slid under the cylinder to catch any sample falling off the cylinder while the Petri dish is being lowered out of the way.

The powder adhering to the cylinder is scraped onto the same weighing paper, and the total amount of sample that has been lifted is weighed.

Caking tendency as measured by this test is rated on the volume of solid sticking to the plunger, calculated as follows, the lower the value, the less pronounced is the caking tendency:

Wt. lifted X30 Tackmess (ml') Wt. of Sample used Example 3 (a) A detergent formulation having the following composition in parts by weight was prepared:

25 parts sodium alkyl benzene sulfonate (same as Example 1) 40 parts sodium tripolyphosphate 7 parts sodium silicate 1 part carboxy methyl cellulose 19 parts sodium sulfate This formulation, when subjected to the lift-tackiness test, was found to have a tackiness value of 1.40 ml.

Additive: Tackiness (ml.) Sodium toluene sulfonate 1.18 Sodium borate 1.39 Disodium benzene disulfonate 0.53 Dipotassium benzene disulfonate 0.7 5

Example 4 (a) A detergent formulation having the following composition in parts by weight was prepared:

19 parts sodium alkyl benzene sulfonate (of Example 1) 1 part lauric isopropanolamide 45 parts sodium tripolyphosphate -5 parts sodium silicate 1 part carboxy methyl cellulose 18 parts sodium sulfate This formulation had a tackiness of 1.65 ml.

(b) To batches of a formulation having the same composition as in (a), there was added 3 parts by weight of one of the following additives, tackiness values being determined as before:

Additive: Tackiness (ml.) Sodium toluene sulfonate 1.71 Sodium borate 1.26 Disodium benzene disulfonate 1.13

Example 5 (a) A detergent formulation having the following composition in parts by weight was prepared:

17 parts sodium alkyl benzene sulfonate (in which the alkyl group is a straight hydrocarbon chain having 10 to 13 carbon atoms) 2 parts lauric ethanolamide 45 parts trisodiumpolyphosphate 5 parts sodium silicate 1 part carboxy methyl cellulose 19 parts sodium sulfate This formulation had a tackiness of 4.86 ml.

(b) To batches of a formulation having the same composition as (a), there was added 3 parts by weight of each of the following additives. Tackiness values were determined as before:

Additive: Tackiness (ml.) Sodium toluene sulfonate 2.33 Sodium borate 1.92 Disodium benzene disulfonate 1.54

Example 6 The effect of varying additive concentration was determined on the following formulation using the lift-tackiness test:

25 parts sodium alkyl benzene sulfonate (as in Example 1) 40 parts sodium tripolyphosphate 7 parts sodium silicate 1 part carboxy methyl cellulose 19 parts sodium sulfate 7 parts water Additive Parts Taekiness (ml.)

N o Additive 8. 2

Disodium Benzene Disulfonate 1. 0 3. 5 o 2.0 2.5

Do 3.0 8.0 Sodium Benzene sulfonate 3.0 8. 6 Sodium Toluene Disulfonate 3. 0 2. 7

I claim: I

1. Process for suppressing the caking tendencies of straight-chain sodium alkyl benzene sulfonate nonsoap detergent containing 9 to 18 carbon atoms in the alkyl portion of the molecule, which comprises uniformly dispersing throughout said detergent 2 to 25% by weight based upon said nonsoap detergent of an anticaking inhibitor selected from the. group consisting of disodium benzene disulfonate, dipotassium benzene disulfonate, disodium toluene disulfonate, and dipotassium toluene disulfonate.

2. Process according to claim 1, wherein the anticaking inhibitor is present in an amount of about 8 to 25% based on nonsoap detergent.

3. Process according to claim 1, wherein the anticaking inhibitor is disodium benzene disulfonate.

4. Process according to claim 1, wherein the anticaking inhibitor is disodium toluene disulfonate.

5. A built particulate solid detergent composition consisting essentially of straight-chain sodium C C alkyl benzene sulfonate nonsoap detergent component having caking tendencies, inorganic sodium salt detergent builder component, and an anticaking inhibitor component to suppress said caking tendencies selected from the group consisting of disodium benzene disulfonate, disodium toluene disulfonate, dipotassium benzene disulfonate, and dipotassium toluene 'disulfonate, the nonsoap detergent and the detergent builder each being present in a proportion within about the range of to 95%, by weight, based on the two, and the anticaking inhibitor, in the range of about 2 to 25 by weight, based on the nonsoap detergent, said composition being obtained by drying an aqueous dispersion of the aforementioned components.

6. A built detergent according to claim 5, wherein the nonsoap detergent is present in a proportion in about the range of to 40%, and the inorganic sodium salt detergent builder, in about the range 60 to 90%.

7. A built detergent according to claim 5, wherein the anticaking additive is present in an amount of about 8 to 20% based on it and nonsoap detergent.

8. A built detergent composition according to claim 6,

wherein the anticaking inhibitor is disodium benzene disulfonate.

9. A built detergentcomposition according to claim 6, wherein the anticaking inhibitor is disodium toluene disulfonate.

10. Heavy-duty particulate solid detergent composition at least about by weight thereof consisting essentially of a mixture of (a) straight-chain sodium alkyl benzene sulfonate nonsoap detergent containing 9 to 18 carbon atoms in the alkyl portion of the molecule, and (b) inorganic sodium salt detergent builder, including condensed sodium phosphate, the weight ratio of (b) to (a) ranging from 1:1 to 10:1, the condensed sodium phosphate being present in a weight ratio to nonsoap detergent ranging from about 1:1 to 3:1; and uniformly dispersed throughout the particles of said composition, an anticaking agent selected from the group consisting of disodium benzene disulfonate, disodium toluene disulfonate, dipotassium benzene disulfonate, and dipotassium toluene disulfonate, said anticaking agent being present in an amount ranging from about 2 to 25%, by weight, based on nonsoap detergent.

11. Composition according to claim 10, wherein the straight-chain sodium alkyl benzene sulfonate nonsoap detergent contains 10 to 14 carbon atoms in the alkyl portion of the molecule.

12. Composition according to claim 11, wherein the anticaking agent is present in an amount of about 8 to20% by weight of the nonsoap synthetic detergent.

13. Composition according to claim 11, wherein the anticaking agent is disodium benzene disulfonate.

14. Composition according to claim 11, wherein the anticaking agent is disodium toluene disulfonate.

References Cited UNITED STATES PATENTS 2,773,833 12/1956 Lewis et al. 252-138 3,174,935 3/1965 Eccles et a1 252161 LEON D. ROSDOL, Primary Examiner.

I. GLUCK, Assistant Examiner. 

5. A BUILT PARTICULATE SOLID DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF STRAIGHT-CHAIN SODIUM C9-C18 ALKYL BENZENE SULFONATE NONSOAP DETERGENT COMPONENT HAVING CAKING TENDENCIES, INORGANIC SODIUM SALT DETERGENT BUILDER COMPONENT, AND AN ANTICAKING INHIBITOR COMPONENT TO SUPPRESS SAID CAKING TENDENCIES SELECTED FROM THE GROUP CONSISTING OF DISODIUM BENZENE DISULFONATE, DISODIUM TOLUENE DISULFONATE, DIPOTASSIUM BENZENE DISULFONATE, AND DIPOTASSIUM TOLUENE DISULFONATE, THE NONSOAP DETERGENT AND THE DETERGENT BUIDER EACH BEING PRESENT IN A PROPORTION WITHIN ABOUT THE RANGE OF 5 TO 95%, BY WEIGHT, BASED ON THE TWO, AND THE ANTICAKING INHIBITOR, IN THE RANGE OF ABOUT 2 TO 25%, BY WEIGHT, BASED ON THE NONSOAP DETERGENT, SAID COMPOSITION BEING OBTAINED BY DRYING AN AQUEOUS DISPERSION OF THE AFOREMENTIONED COMPONENTS. 